Thanks for this code! I've taken the liberty to extend the code a bit, but be careful, it has not been tested very much till now.

Added features:
- A button to set "now" and clear the value (set btnNowText:'' to hide the button).
- A dateTimeFormat which makes the submitted value format more flexible. It's also used as the input for setValue (@Dmoney: Does this solve your problem?).

There are 3 known issues:
- The button width changes when the button text changes which looks a bit strange in my eyes (Any idea how to make the button stay on the widest width concerning both possible texts)?
- I'm not quite sure if this getSubmitData-thing is a bug.
- The readOnly-config doesn't work so far.